Novel TCP method to suppress the time delay effect in heterogeneous radio systems

The heterogeneous radio system is one approach to cognitive radio and a great candidate for creating a new fundamental network that improves the efficiency of frequency resource usage. In this paper, our target is to aggregate the adaptive link of multiple radio systems into a single rich link. Generally, time delays differ among multiple different radio systems, which cause the TCP performance to deteriorate. We propose two schemes to avoid the degradation. The first is delay adjustment and the second is TCP customizing. The delay adjustment scheme eliminates the time delay difference among multiple or between two links, while the customized TCP scheme performs the function to turn the slow start process of TCP on/off adaptively. When the slow start process is turned off, the congestion window is updated for the effective throughput, based on estimation from the radio environment information instead of the slow start process.